FIG. 6 shows an ordinary structure for a connecting pin device for machine operating links adapted to control the posture of a working unit. The structure of the connecting pin device for machine operating links shown in the drawing will be described below. Links 9R and 9L on one side are spaced away from and opposed to each other. Provided coaxially in end portions of these links 9R and 9L are pin boss portions 2R and 2L, into which a pin 1 is to be fitted. Disposed between these pin boss portions 2R and 2L is a cylindrical pin boss portion 2M, which is provided at one end of a link 9 on the other side, and the pin 1 is inserted into these pin boss portions 2R, 2M and 2L after mating their pin holes with each other, thus effecting pin joint connection of the links 9R, 9L and 9. This structure, however, has the following problem: To facilitate the insertion and extraction of the pin 1, the inner diameter of pin boss portions 2R and 2L and that of bushes 2, which are fitted within the pin boss portion 2M, are made larger than the outer diameter of the pin 1 (In the case, for example, of a connecting pin device for machine operating links for the working unit of a hydraulic excavator or the like, the pin 1 is inserted by "a clearance fit" with a clearance of about 1 mm or less on either side). As a result, a play (unstableness) in the radial direction R is generated in the pin connection portion. Further, to prevent the pin boss portions 2R, 2L and 2M from interfering with each other due to machining or assembly errors, etc. when placing the pin boss portion 2M between the pin boss portions 2R and 2L, the distance between the pin boss portions 2R and 2L is made larger than the width of the pin boss portion 2M. As a result, there is generated in the pin boss portion 2M a slide play (unstableness) in the axial direction S. Such a clearance or play in the joint portions causes an inertia of motion each time the movement of the machine operating links stops (for example, each time the raise movement of the working unit stops), thereby causing a rattling sound. Further, the play in the joint portions makes it impossible to suppress the inertia of motion of the working unit when the machine operating links stop moving, with the result that the shaking of the working unit cannot be stopped quickly, thus constituting an obstacle to operation. As a means for solving this problem, a structure has been proposed in which the clearance in the axial direction S is compensated for (see, for example, Japanese Utility Model Laid-Open No. 58-52315). Although it helps to avoid a play or an inertia of motion due to a play, this structure, as it is, cannot eliminate the play in the radial direction R or suppress the shaking when the machine stops its raise movement.